This invention relates to arylene sulfide polymers and their use as coating materials. In one aspect, the invention relates to the preparation of poly(arylene sulfide)s which are suitable for coating applications in which relatively low-temperature curing is desirable.
Poly(arylene sulfide) resins have properties such as thermal stability and chemical resistance which make the resins useful for coating substrates. Coating-grade poly(arylene sulfide) resins are conventionally prepared in a reaction mixture containing p-dichlorobenzene, sodium hydroxide, a sulfur source such as sodium hydrosulfide, and a polar organic reaction medium such as N-methylpyrrolidone. The resulting poly(p-phenylene sulfide) can be applied to a substrate as a finely-divided solid in slurry and cured by heating in air to form a tough, chemical-resistant coating on the substrate.
In order to form a continuous, smooth coating on the substrate, it is generally necessary to cure the poly(p-phenylene sulfide) at a temperature above about 370.degree. C. Such a cure temperature has the disadvantages of requiring special heating equipment, increasing the cost of the coating procedure, and limiting the substrates and environments with which the coating can be used. Some substrate materials will be degraded by exposure to such a high cure temperature.
It is therefore an object of the present invention to provide new poly(arylene sulfide) coating formulations. It is a further object to provide methods for preparing and treating poly(arylene sulfide) coating resins which reduce the cure temperature of coating formulations in which the resins are employed. It is a further object to provide low-temperature methods of coating a substrate with a poly(arylene sulfide).